They are certainly in touch with *their* feelings. They deserve respect, I guess, but probably think it's beneath them to show any to other people. All rights, no obligations.
It's also likely somebody's telling them that it's okay to act on their anger, and to act in this way. That's something they don't learn in schools and schools really have trouble teaching to those who dismiss school as oppression. But this isn't how you recover your honor or dignity, at least not in mainstream American culture for the last century or so; it is how you go into the penal system for a good long time.
Not only that, but it shows that they assumed that those they were after were first and foremost members of a group, and that collectively punishing the group is a fine way to doing things, that individual identity is thoroughly wrapped up in some salient single group marker. Their gang, their family, their neighborhood, their skin color, their speech, whatever. It's hard to defend "I'm mostly a member of my group" for most social or political views and condemn this with a straight face. (Now, for petty little things, yeah; I'm a teacher, and when dealing with students and school administrators that's my primary identity; I play violin, and when there's a conductor that's my identity. I'm a home owner, and that's one of my identities. But I have a lot and they shift constantly.)
That "one identity is paramount and unites you with those with like identity" is the kind of thinking behind the worst of the racist stereotypes that we (and probably the shooters) would condemn. My mother, for instance, believed all blacks were thieves. Why? Because when she was 15 or 16 the black clerk at her step-father's store was a thief. He represented everybody that was like him, his crime or sin was the crime or sin of everybody in his group (made worse that his theft was just letting other blacks come into the store and take whatever they needed while her family was at church and the store was supposedly closed). Her mother wasn't feeling well one day at church, they returned early, and he was homeless 10 minutes later. My mother's thinking is very KKK-like in "there's one group identity and everybody shares the properties of everybody else in that group." Such drivel.
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